This invention relates to winding devices for dynamoelectric machines, and in particular, to axial coil insertion apparatus for inserting prewound coils into the slots of a stator assembly of a dynamoelectric machine. While the invention is described in conjunction with its application to induction motors, those skilled in the art will recognize the wider applicability of the invention disclosed hereinafter.
Axial insertion devices, of a type generally described in the U.S. Pat. No. 2,432,267, to Adamson, are widely used by motor manufacturers for inserting prewound coils into the slots of stator assemblies of dynamoelectric machines, particularly of the induction motor type. Commonly, axial insertion devices include an annular array of blades spaced with respect to one another so as to define gaps therebetween. The blades conventionally have a radially outward facing surface which abuts the teeth of the stator laminations forming the stator core of a conventional stator assembly for a dynamoelectric machine. The stator laminations have a central bore opening in them. A plurality of winding receiving slots extend radially outwardly from and communicate with the bore opening. That part of the lamination between successive slots delimits the stator teeth. The teeth have inboard faces about the bore opening which are spaced from one another to permit the communication between the slots and the bore opening. The gap between successive blades corresponds to the opening between successive teeth of the stator lamination. A device, known in the art as a stripper, is a fluted member having arms designed to extend through the gap between adjacent blades. The stripper is mounted for reciprocal movement between a first position below a free end of the blades and a second position where the stripper forces the prewound coils of wire over the free end of the blades, thereby depositing the coils in the slots of the stator core. It also is conventional to insert insulation wedges simultaneously with winding insertion the insulation wedges closing the communicative path between the bore opening and the winding receiving slots after winding placement.
Although axial insertion machines are widely used for motor manufacturing, the insertion process is not without complications. It is known that wire coils of certain sizes will tend to wedge or lock in the blade gaps, thus damaging the coils or jamming the coil insertion machine. Certain wire sizes required for the construction of a particular induction motor stator assembly winding may not be capable of insertion with a particular set of blades. Winding insertion success depends on the ratio of the gap width between adjacent blades and the diameter of the wire used for the motor winding. Although a variety of blade sets having different gap width normally are available to meet this contingency, the teardown and set-up time required for blade set change-over is disruptive of production schedules.
One solution to the jamming or wire turn fouling problem is given in the U.S. Pat. No. 3,689,976, to Donovan, issued Sept. 12, 1972. In Donovan, preselected ones, and preferably alternate ones of the blades are attached to the stripper so that the attached blades move with the stripper during the insertion stroke of the device. While Donovan works well for its intended purpose, it can not be used efficiently over a very wide range of motor types. As will be appreciated by those skilled in the art, the prewound coils used in axial insertion machines consist of a plurality of coil sets which are constructed from a plurality of individual wire turns. Each of the coil sets are intended to span some preselected number of teeth of the stator lamination. The wire turns comprising a coil set conventionally include a straight conductor run portion carried by the stator slots, and an end turn portion spanning a preselected number of stator teeth along the outboard faces of the stator core. The end turn portions connect successive ones of the straight conductor run portions of the wire turn. The physical dimensions of the coil sets spanning the fewest number of stator teeth is substantially smaller than the physical dimensions of the coil sets spanning the greatest number of stator teeth. While the physical attributes of the prewound coils generally are not a detriment when a single winding is inserted by the device, they can and do cause problems when multiple windings are inserted simultaneously. Since the Donovan device uses blades attached to the stripper to achieve the relative movement between blades, the movable blades necessarily move a long distance. The distance of movement is considerably greater than the height dimension of the coil sets, the height dimension being equivalent to the straight conductor run portions of the wire turn forming the coil set. Because of the dimensions involved, the movable blades often interfere with the insertion of the windings, particularly in the short span coil set members of the prewound coil. When interference occurs, the solution has been replacement of the movable blades with conventional fixed blades. Consequently, the desirable effect obtained with the moving blade concept described in Donovan is lost on a great number of motors during motor manufacture.
The invention disclosed hereinafter offers a new solution to the problems encountered with prior art devices using movable blades. It enables the entire annular array of blades to move relative to one another, regardless of blade position within the array by providing short stroke blade movement. Short stroke blade movement is achieved by moving alternate blades of the blade set reciprocally and out of phase with one another.